|
|
A160995
|
|
The smallest positive integer neither a divisor of n nor coprime to n.
|
|
2
|
|
|
4, 6, 6, 10, 4, 14, 6, 6, 4, 22, 8, 26, 4, 6, 6, 34, 4, 38, 6, 6, 4, 46, 9, 10, 4, 6, 6, 58, 4, 62, 6, 6, 4, 10, 8, 74, 4, 6, 6, 82, 4, 86, 6, 6, 4, 94, 9, 14, 4, 6, 6, 106, 4, 10, 6, 6, 4, 118, 8, 122, 4, 6, 6, 10, 4, 134, 6, 6, 4, 142, 10, 146, 4, 6, 6, 14, 4, 158, 6, 6, 4, 166, 8, 10, 4, 6
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
2,1
|
|
COMMENTS
|
a(1) doesn't exist because 1 is coprime to all integers.
|
|
LINKS
|
|
|
FORMULA
|
a(p) = 2p, for all primes p.
|
|
PROG
|
(PARI) a(n)=my(f=factor(n), b); forprime(p=2, , if(n%p, b=p*f[1, 1]; break)); for(i=1, #f[, 1], b=min(b, f[i, 1]^(f[i, 2]+1))); b \\ Charles R Greathouse IV, Apr 05 2013
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|